title: Validation of the new classification of pauci-immune glomerulonephritis in a United States cohort and its correlation with renal outcome.
abstract: BACKGROUND
  Renal biopsies provide important diagnostic and prognostic information in ANCA associated glomerulonephritis. A new classification for prognostication of pauci-immune glomerulonephritis (GN) based on four categories (Mixed, Crescentic, Sclerotic and Focal) was proposed by an international working group of renal pathologists (IWGRP). The goal of our study was to apply the proposed classification system to a United States cohort of vasculitis patients and determine the association of IWGRP class with estimated glomerular filtration rate (eGFR) at one year.
  
  
  METHODS
  Seventy-six cases of pauci-immune glomerulonephritis diagnosed from 1995 to 2011 from a single center were identified for this retrospective study. Clinical data were collected by abstraction from medical records. Histology was reviewed by a pathologist and classified according to the new classification. MDRD formula was used to calculate eGFR. We correlated IWGRP class to renal function at presentation and at one year. ×2, ANOVA, and linear regression analysis were performed as appropriate.
  
  
  RESULTS
  Renal biopsies were categorized as focal: n = 20, crescentic: n = 18, mixed: n = 27, sclerotic: n = 11. The baseline e-GFR was lowest in the crescentic class and highest in the focal class. In linear regression analysis investigating e-GFR at 1 year; age and baseline e-GFR were independent predictors of e-GFR at 1 year.
  
  
  CONCLUSIONS
  The e-GFR at diagnosis and age were predictors of e-GFR at 1 year. Pathologic class at diagnosis may also be a helpful tool in risk stratification at diagnosis.
authors.affiliation: Medicine, The Johns Hopkins Hospital and School of Medicine, Baltimore, Maryland, USA. gduvura@jhmi.edu.
authors.forename: Carla L
authors.initials: CL
authors.lastname: Ellis
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Manno
authors.forename: John P
authors.initials: JP
authors.lastname: Havill
authors.forename: Lorraine C
authors.initials: LC
authors.lastname: Racusen
authors.forename: Duvuru
authors.initials: D
authors.lastname: Geetha
mesh_terms: D001327:Autoimmune Diseases / Q000145:classification* / Q000473:pathology* / Q000503:physiopathology; D001706:Biopsy / Q000379:methods; D015331:Cohort Studies; D005260:Female; D005919:Glomerular Filtration Rate; D005923:Glomerulosclerosis, Focal Segmental / Q000145:classification* / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D009626:Terminology as Topic; D014481:United States